On 29 May 1670 he was ordained as a priest of the Church of England. He was vicar of the parish of Bobbing in Kent, 1673-4, and then curate to his father at All Saints', Hastings. During this time Oates was charged with perjury having accused a schoolmaster in Hastings of sodomy. Oates was put in jail, but escaped and fled to London.[2] In 1677 he was appointed as a chaplain of the ship Adventurer in the Royal Navy.[5]:54-5 He was soon accused of buggery which was a capital offence and spared only because of his clergyman's status.[5]:54-5

When he returned to London, he rekindled his friendship with Israel Tonge. Oates explained that he had pretended to become a Catholic to learn about the secrets of the Jesuits and that, before leaving, he had heard about a planned Jesuit meeting in London.

Oates and Tonge wrote a lengthy manuscript that accused the Catholic Church authorities in England of approving an assassination of Charles II. The Jesuits were supposedly to carry out the task. In August 1678, King Charles was warned of this alleged plot against his life by the chemist Christopher Kirkby, and later by Tonge. Charles was unimpressed, but handed the matter over to one of his ministers, Thomas Osborne, Earl of Danby; Danby was more willing to listen and was introduced to Oates by Tonge.

Oates reveals the plot to the King; one of a set of playing cards depicting the Plot by Francis Barlow, c. 1679

Although Oates may have selected the names randomly, or with the help of the Earl of Danby, Colman was found to have corresponded with a French Jesuit who was confessor to Louis XIV, which was enough to condemn him. Wakeman was later acquitted. Despite Oates' unsavoury reputation, his confident performance and superb memory made a surprisingly good impression on the Council. When he named "at a glance" the alleged authors of five letters supposedly written by leading Jesuits the Council were "amazed". As Kenyon remarks, it is surprising that it did not occur to the Council how easy this would be if Oates had written them all himself.[5]:79

On 6 September 1678, Oates and Tonge had approached an Anglican magistrate, Sir Edmund Berry Godfrey and had sworn an affidavit before him detailing their accusations. On 12 October, Godfrey disappeared and five days later his dead body was found in a ditch at Primrose Hill; he had been strangled and run through with his own sword. Oates subsequently exploited this incident to launch a public campaign against the "Papists" and alleged that the murder of Godfrey had been the work of the Jesuits.

On 24 November 1678, Oates claimed the Queen was working with the King's physician to poison the King. Oates enlisted the aid of "Captain" William Bedloe, who was ready to say anything for money. The King personally interrogated Oates, caught him out in a number of inaccuracies and lies, and ordered his arrest. However, a few days later, with the threat of a constitutional crisis, Parliament forced the release of Oates, who soon received a state apartment in Whitehall and an annual allowance of £1,200.

On 31 August 1681, Oates was told to leave his apartments in Whitehall, but he remained undeterred and even denounced the King and his Catholic brother, the Duke of York. He was arrested for sedition, sentenced to a fine of £100,000 and thrown into prison.

Engraving of a pilloried Titus Oates

When the Duke of York acceded to the throne in 1685 as James II, he had Oates retried, convicted and sentenced for perjury, stripped of clerical dress, imprisoned for life, and to be "whipped through the streets of London five days a year for the remainder of his life."[7] Oates was taken from his cell wearing a hat with the text "Titus Oates, convicted upon full evidence of two horrid perjuries" and put into the pillory at the gate of Westminster Hall (now New Palace Yard) where passers-by pelted him with eggs. The next day he was pilloried in London and the third day was stripped, tied to a cart, and whipped from Aldgate to Newgate. The next day, the whipping resumed. The presiding judge was Judge Jeffreys who stated that Oates was a "shame to mankind". So severe were the penalties that it has been suggested that the aim was to kill Oates by ill-treatment, as Jeffreys and his colleagues openly regretted that they could not impose the death penalty in a case of perjury.

Oates spent the next three years in prison. In 1689, upon the accession of the Protestant William of Orange and Mary, he was pardoned and granted a pension of £260 a year, but his reputation did not recover. The pension was later suspended, but in 1698 was restored and increased to £300 a year. Oates died on 12 or 13 July 1705, by then an obscure and largely forgotten figure.